Engine core rotor shaft structure for gas turbine engine

ABSTRACT

An engine core rotor shaft structure for gas turbine engine is disclosed, which includes an outer annular shaft body, an inner annular shaft body, high pressure turbine (HPT) rotor blades radially connected between the outer annular shaft body and the inner annular shaft body to hold the inner annular shaft body in the rear section of the outer annular shaft body, and a can type combustor mounted in a receiving chamber inside the outer annular shaft body to enlarge the diameter of the core shaft, to avoid vibration due to resonance, to save space occupation, to eliminate dissipation of heat, and to improve the thermal efficiency of the gas turbine engine.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a rotor and, more particularly, to an engine core rotor shaft structure for use in the gas turbine engine of an axial type or centrifugal type compressor.

[0003] 2. Description of Related Art

[0004]FIG. 1 illustrates a conventional gas turbine engine 9 formed of a compression section 91, a combustion section 92, and a turbine section 93. The gas turbine engine 9 comprises a casing 94, an engine core rotor 95 installed in the casing 94, and an annular combustor 96 mounted in the annular space defined within the casing 94 around the core shaft 950 of the engine core rotor 95. The intake air is compressed and delivered (compressor rotor 941 and stator 951) to the combustor 96 at substantially increased pressure and temperature. There, the fuel is burned and the temperature raised to a higher value. Then, the hot, pressurized combustion gases expand through a series of rotating turbine wheel and blade assemblies (high pressure turbine 952, power turbine 971) resulting in shaft power output, propulsive thrust, or a combination of the two.

[0005] The diameter of the core shaft 950 is limited in the configuration of a conventional gas turbine. Due to limited diameter, it is difficult to improve the rigidity of the core shaft 950 and its vibrations. Vibration due to resonance is a serious problem which is more apparent in a high-speed micro gas turbine engine.

[0006] Further, because the annular combustor 96 is installed in the annular space within the casing 94 around the core shaft 950, the space occupation of the annular combustor 96 does not meet the requirement for compact design. Furthermore, the arrangement of the annular combustor 96 around the core shaft 950 may cause heat dissipation.

[0007] Therefore, it is desirable to provide an engine core rotor for gas turbine engine that eliminates the aforesaid drawbacks.

SUMMARY OF THE INVENTION

[0008] It is the main object of the present invention to provide an engine core rotor for gas turbine engine, which greatly enlarges the diameter of the shaft to increase in the rigidity and avoid vibration due to resonance of the shaft, so as to further improve the stability and service life of the engine core rotor. It is another object of the present invention to provide an engine core rotor for gas turbine engine, which keeps the combustor arranged inside the shaft to meet compact design requirement, so as to reduce heat dissipation and improve the thermal efficiency of the gas turbine engine.

[0009] To achieve these and other objects of the present invention, the engine core rotor shaft structure for gas turbine engine comprises an outer annular shaft body, an inner annular shaft body, and HPT rotor blades. The outer annular shaft body is a hollow annular shape extended in axial direction relatively, comprising a front section, a rear section, and a middle section connected between the front section and the rear section and defining a receiving chamber. The outer diameter of the inner annular shaft body is smaller than the inner diameter of the rear section of the outer annular shaft body. The HPT rotor blades are radially extended outwardly from the inner annular shaft body and fixedly connected to the rear section of the outer annular shaft body. The inner annular shaft body is coaxially provided in the rear section of the outer annular shaft body. Because the diameter of the outer annular shaft body is greatly increased, the rigidity of the shaft of the gas engine rotor is improved, and the critical speed of the shaft is increased, and therefore the stability of the rotation of the shaft is improved and, the service life of the shaft is prolonged. A can type combustor is mounted in a receiving chamber inside the outer annular shaft body to save space occupation, to eliminate dissipation of heat, and to improve the thermal efficiency of the gas turbine engine. A front annular shaft body of relatively smaller diameter may be provided inside the front section of the outer annular shaft body. HPC rotor blades are radially extended outwardly from the periphery of the front annular shaft body and fixedly connected to the front section of the outer annular shaft body. The front annular shaft body is coaxially mounted inside the front section of the outer annular shaft body.

[0010] Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a schematic drawing showing an axial type gas turbine engine constructed according to the prior art.

[0012]FIG. 2 is a schematic drawing showing an axial type gas turbine engine constructed according to the present invention.

[0013]FIG. 3 is a detailed schematic drawing showing a centrifugal type gas turbine engine constructed according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Referring to FIG. 2, the axial type gas turbine engine shown in the drawing is a micro gas turbine engine (thrust force below 200 pounds, or shaft power output 250 horsepower) whose rotory speed is usually beyond 60,000 rpm. As illustrated, the engine core rotor 71 is mounted inside a casing 72, which has a compression section 73 at the front side, a combustion section 74 in the middle, and a turbine section 75 at the rear side.

[0015] The shaft of the engine core rotor 71 comprises an outer annular shaft body 1, an inner annular shaft body 2, a plurality of HPT rotor blades 3, a front annular shaft body 5, a plurality of HPC rotor blades 6, and a combustor 4.

[0016] The outer annular shaft body 1 is a hollow annular shape extended in axial direction relatively, comprising a front section 11, a rear section 12, and a middle section defining a receiving chamber 13. The combustor 4 is mounted in the receiving chamber 13. In order to save manufacturing cost, the combustor 4 can be a can type combustor.

[0017] The inner annular shaft body 2 is coaxially mounted in the rear section 12 of the outer annular shaft body 1. The outer diameter of the inner annular shaft body 2 is smaller than the inner diameter of the rear section 12 of the outer annular shaft body 1. The HPT rotor blades 3 are radially extended from the periphery of the inner armular shaft body 2 and fixedly connected to the inside wall of the rear section 12 of the outer annular shaft body 1.

[0018] The front annular shaft body 5 is coaxially mounted inside the front section 11 of the outer annular shaft body 1. The HPC rotor blades 6 are radially extended from the periphery of the front annular shaft body 5 and fixedly connected to the inside wall of the front section 11 of the outer annular shaft body 1.

[0019] When intake air passed from the front side of the casing 72 into the compression section 73, the compressor stator blades 731 gives a 10 diffusion effect to intake air, and the HPC rotor blades 6 work to compress intake air, and compressed air is then combusted in the can type combustor 4. Hot compressed gas rapidly flows out of the can type combustor 4 toward the HPT rotor blades 3 and the power turbine blades 81, thereby causing the engine core rotor 71 and the power turbine 8 to be rotated.

[0020] As indicated above, the diameter of the outer annular shaft body 1 is greatly enlarged, the front annular shaft body 5 and the inner annular shaft body 2 are respectively provided in the front and rear sides of the outer annular shaft body 1. Therefore, the outer annular shaft body 1 has a high rigidity, and can be designed to work under a high critical speed to improve the stability of the system and prolong its service life.

[0021] Because the diameter of the outer annular shaft body 1 is greatly increased, the combustor 4 can be directly mounted inside the outer annular shaft body 1 to meet the requirement for compact design. In comparison with conventional designs of equal output power, the invention greatly reduces the dimensions and weight of the engine core rotor. According to experimentations, the dimensions and weight of the invention can be about 80% of a conventional gas turbine engine, or 20% of a conventional gasoline.

[0022] Further, because the combustor 4 is provided inside the outer annular shaft body 1 and the casing 72, the design of the present invention effectively eliminate the problem heat dissipation, and greatly improves the thermal efficiency of the gas turbine engine.

[0023]FIG. 3 shows an alternate form of the engine core rotor shaft structure for use in a centrifugal type gas turbine engine according to the present invention. According to this embodiment, the HPT rotor blades 30 are radially extended from the periphery of the inner annular shaft body 20 and fixedly connected to the inside wall of the rear section 120 of the outer annular shaft body 10, and a combustor 40 is mounted inside the outer annular shaft body 10. However, the front section of the outer annular shaft body 10 is directly fixedly fastened to the compressor rotor 50.

[0024] During operation, the centrifugal effect of the compressor rotor 50 compresses intake air, and the heat exchanger 76 increases the temperature of compressed air. Compressed air flows from the heat exchanger 76 along grooves of the outer annular shaft body 10 through air holes 401 into the combustor 40 where compressed air is combusted. Hot compressed gas immediately flows out of the combustor 40 toward the HPT rotor blades 30 to rotate the inner annular shaft body 20 and the outer annular shaft body 10, and then toward the power turbine blades 810 to rotate the power turbine 80. At final, waste gas flows into the heat exchanger 76 to make a heat exchanging action, and then flows out of the gas turbine engine via the exhaust passage 721. According to this alternate form, the outer annular shaft body 10 has a great diameter, and the combustor 40 is provided inside the outer annular shaft body 10.

[0025] Although the present invention has been explained in relation to its preferred embodiments, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed. 

What is claimed is:
 1. An engine core rotor shaft structure for gas turbine engine comprising: an axially extended outer annular shaft body, said outer annular shaft body comprising a front section, a rear section, and a receiving chamber defined in a middle section connected between said front section and said rear section; an inner annular shaft body, said inner annular shaft body having an outer diameter smaller than the inner diameter of the rear section of said outer annular shaft body; and a plurality of high pressure turbine (HPT) rotor blades respectively radially extended outwardly from said inner annular shaft body and fixedly connected to the rear section of said outer annular shaft body in order to make said inner annular shaft body coaxially provided in the rear section of said outer annular shaft body.
 2. The engine core rotor shaft structure for gas turbine engine as claimed in claim 1 further comprising a combustor mounted in the receiving chamber of said outer annular shaft body.
 3. The engine core rotor shaft structure for gas turbine engine as claimed in claim 2, wherein said combustor is a can type combustor.
 4. The engine core rotor shaft structure for gas turbine engine as claimed in claim 1 further comprising: a front annular shaft body, said front annular shaft body having an outer diameter smaller than the inner diameter of the front section of said outer annular shaft body; and a plurality of high pressure compressor (HPC) rotor blades radially extended outwardly from the periphery of said front annular shaft body and fixedly connected to the front section of said outer annular shaft body in order to make said front annular shaft body coaxially mounted inside the front section of said outer annular shaft body.
 5. The engine core rotor shaft structure for gas turbine engine as claimed in claim 1, which is used in an axial type gas turbine engine.
 6. The engine core rotor shaft structure for gas turbine engine as claimed in claim 1, which is used in a centrifugal type gas turbine engine. 